Proximity Sensor vs Photoelectric Sensor: What’s The Difference?

In automation applications, proximity and photoelectric sensors are commonly utilized. They do, however, differ in some ways. We’ll look at the two sensors in this article and see how they differ. Let’s take a look at each of them individually.

What is a Proximity Sensor?

A proximity sensor detects the presence of things in close proximity without requiring physical contact. This can be accomplished by using an electromagnetic radiation beam or electromagnetic field where the return signal field varies with the presence of any object in the vicinity. A target is an object that is detected by a proximity sensor.

A proximity switch is another term for it.  There appears to be a transformer-like link between the sensing object and the sensor. Due to the lack of mechanical parts and direct contact, proximity sensors have a high level of dependability and long functional life.

Proximity sensors are available in types that detect ferrous and non-ferrous metal items utilizing high-frequency oscillation and capacitive models that detect non-metal objects. These models come with environmental heat, water, and chemical resistance.

Features of the Proximity Sensor

We’ll look at the features of a proximity sensor to see what it’s all about. It has the following characteristics:

Contactless Sensing

Because proximity sensor senses an object without contacting it, they do not create damage or abrasion to it. Limit switches detect objects by contacting them; however, Proximity Sensors detect object electrically, without touching it.

Unaffected by Surface Condition

Proximity sensors sense an object’s physical changes and are virtually totally unaffected by the color of the object’s surface.

Suitability for a Wide Range of Applications

Unlike traditional optical detection, proximity sensors can be used in damp conditions and over a wide temperature range. They can withstand temperatures ranging from 40 to 200 degrees Celsius.

Proximity sensors can also be found in smartphones running Android or iOS. It uses basic IR technology to turn on and off the display depending on your needs.

Longer Service Life

Because semiconductor outputs are used in  proximity sensors, they don’t have any moving parts affected by the working cycle. As a result, it’s service life is longer than standard sensors.

High-Speed Response

Compared to switches that require contact for detecting, proximity sensors have a faster reaction rate.

What is a Photoelectric Sensor?

Photoelectric sensors are sufficiently adaptable that they can handle the majority of industrial sensing challenges. Since photoelectric technology has improved so quickly, they can now detect targets with a diameter of less than 1 mm from a distance of up to 60 meters. Many photoelectric setups are possible, which are classified based on how light is emitted and supplied to the receiver.

However, all photoelectric sensors have a few standard components: a phototransistor receiver or photodiode to detect emitted light,  an emitter light source (LED, laser diode), and accompanying circuitry to amplify the reception signal. The emitter, also known as the sender, sends a beam of light to the sensing receiver, which can be visible or infrared.

The fundamentals of operation for all photoelectric sensors are the same. The light-on classifications and dark-on refer to light reception and sensor output activity, respectively, making it simple to identify their output. The sensor is dark-on if it generates output when no light is received. It’s light-on now that the light has been received. Unless the sensor is user-configurable, you must decide whether you want it to be dark-on or light-on before buying it. (In that scenario, the output style can be selected by wiring the sensor or turning a switch during installation.)

What is through-Beam sensor

Through-beam sensors are the most efficient photoelectric sensors. The emitter, isolated from the receiver by a different housing, emits a steady beam of light; detection happens when anything passes between the two and breaks the beam. Despite its durability, the through-beam photoelectric arrangement is the least popular.

The installation, procurement, and alignment of the emitter and receiver in two opposed locations, which may be reasonably far apart, is time-consuming and costly. With newly developed designs, through-beam photoelectric sensors often give the maximum sensing distance of photoelectric sensors – 25 meters and beyond is now standard.

New laser diode emitter models can broadcast a 60 m well-collimated beam for greater precision and detection. Some through-beam laser sensors can detect an object as small as a fly at these distances; at close range, that number drops to 0.01 mm. However, while the precision of these laser sensors improves, the response speed remains the same as that of non-laser sensors — roughly 500 Hz.

Effective sensing in the presence of heavy airborne pollutants is a feature specific to through-beam photoelectric sensors. There is an increased risk of erroneous triggering if contaminants accumulate directly on the emitter or receiver. Some manufacturers, however, now include warning outputs in the sensor’s circuitry that monitor the quantity of light reaching the receiver. If the detected light falls below a certain threshold without a goal, the sensor issues a warning through a built-in LED or an output wire.

Commercial and industrial uses abound for through-beam photoelectric sensors. They detect objects in the route of garage doors at home, for example, and have prevented the smashing of many a bicycle and car. On the other hand, objects on industrial conveyors can be sensed anywhere between the emitter and receiver, as long as gaps separate the monitored objects and the sensor light does not “burn through” them. (Light-colored or Thin objects may allow generated light to pass through to the receiver, resulting in burn-through.)

Working Principle

Three fundamental ways of target detection are available with photoelectric sensors:

Diffused Mode or Proximity-Sensing Mode

The transmitter and receiver are both housed together in this sensing mode. The target reflects the light from the transmitter at various angles. The target is detected as some of the light reflected returns to the receiver. Diffused mode with background suppression, diffused convergent beam mode, and diffused mode with mechanical background suppression are some variations of this mode.

Retro-Reflective Mode

The transmitter and receiver are housed in the same enclosure as in the prior mode. The light from the transmitter has reflected by the receiver using a reflector. Retro-reflective mode with foreground suppression and retro-reflective mode for precise object detection are two other versions of this mode.

Thru-Beam Mode or Opposed Mode

The Receiver and transmitter are housed separately in two housings. The receiver receives the light from the transmitter, and the receiver’s output is activated when a target breaks the light beam. This mode is the most efficient of the three since it permits photoelectric sensors to have the largest sensing ranges imaginable.

Proximity Sensor vs Photoelectric Sensor: What’s The Difference?

The following are the distinctions between proximity and a photoelectric sensor.

Method of Detection

A proximity sensor identifies an object without physically touching it using an electromagnetic field. The information is then converted into an electrical signal by the processor.

The object is detected by a photoelectric sensor, which employs light to do so. The optical signal transmitted from the sensor’s emitting component is modified by the detecting object, which is then detected by the sensor’s receiving part, which generates a matching output signal.

Response Time

The photoelectric sensor responds in microseconds thanks to the employment of an optical beam for detection and comprehensive electronic circuitry, allowing it to be easily employed on a high-speed production line. Because light travels rapidly, the sensor’s response time is incredibly quick, and all circuits are made up of electronic components, the sensor does not perform mechanical activities. The proximity sensor has a slightly longer response time than the photoelectric sensor. In milliseconds, it detects objects.

Sensing Range

Compared to the photoelectric sensor, the proximity sensor has a limited detection range. A proximity sensor has a sensing range of less than one inch (25,44 mm). A photoelectric sensor has a sensing range of up to 800 feet. (243,8 meters)

Cost

A proximity sensor costs less on average than a photoelectric sensor. There are many different types of photoelectric sensors and other detection methods. As a result, the average price is high.

Sensor Size

A photoelectric sensor has a smaller footprint than a proximity sensor.

Dust and Dirt

The photoelectric sensor has the disadvantage that detection may be impossible if the lens surface is covered in dust or debris and light transmission is impeded. This is not a problem with the proximity sensor.

Resolution

The photoelectric sensor’s exceptionally high resolution is due to advanced design innovations that resulted in a very small spot beam and a one-of-a-kind optical system for receiving light. These advancements allow for the detection of extremely small objects as well as exact location detection. The proximity sensor can detect larger items.

Color Identification

Because the object color affects the reflection and absorption properties for a given incident optical wavelength, distinct colors can be detected using a photoelectric sensor as a difference in optical intensity. The proximity sensor is unable to distinguish between the hues.

Adjustment

Because the beam is visible, positioning the beam on an item with a photoelectric sensor is easy. A proximity sensor’s settings are a little tricky to figure out.

Conclusion

We hope you found this article on the difference between Proximity Sensors and Photoelectric Sensors to be helpful. The two sensors are unique because they are useful in their applications.

For more details on Proximity Sensors and Photoelectric Sensors, feel free to contact us at ICRFQ. We manufacture the best electrical components and sensors in China.

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